The overall objective of the proposed research is to isolate from plants of the family Compositae new compounds which may have antitumor, schistosomicidal and other biological properties. Many of the plants to be studied are used as medicinal plants in the countries of their origin. Emphasis will be placed on sesquiterpene lactones which in addition to their potential biological activity are also useful for the clarification of evolutionary relationships in this important plant family. Partial syntheses of reference compounds are to be carried out and the applicability of a newly discovered biomimetic type furan synthesis for the preparation of furanoterpene and the lactones derived from them will be explored.